Towards the realization of a single-mode photonic crystal fiber in the middle infrared

摘要

Photonic crystal fibers confine light within a periodic array of elements. We used multiple extrusions of silver halide (AgCl_xBr(1-x)) crystalline materials to fabricate photonic crystal fibers, which are transparent in the middle infrared (mid- IR) in the spectral range 2-20μm. The cores of these fibers consisted of pure silver bromide (AgBr) of refractive index n=2.16, and the cladding area included concentric rings of tens of fiberoptic elements made of pure silver chloride (AgCl), of a lower refractive index n=1.98. Simulations on photonic crystal structures showed that all the fabricated fibers guide a small number of modes. Furthermore, adding rings to such a structure should lower the number of bound modes in the core. We measured the attenuation and the output power distribution of these fibers and carried out spectroscopic measurements in the mid- IR. Good correlation was found between the experimental and the theoretical results. These findings will pave the way for the fabrication of single-mode fibers in the mid- IR range.